Fornia



Oct. 8, 1929.

F. A. KOLSTER RADIO APPARATUS Original Filed Jan. 3, 1923 INVENTOR. m 4mm BY M 95. com

1 ATTORNEY.

Patented Oct. 8, 1929 UNITED ,STATES PATENT OFFICE FREDERICK A. KOLSTER,OF PALO ALTO, CALIFORNIA, ASSIGNOR TO FEDERAL TELE- GRAPH COMPANY, OFSAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALI- FORNIA RADIO APPARATUSApplication filed January 3, 1923, Serial No. 610,421. Renewed March 6,1929.

My invention relates to apparatus for receiving radio telegraphic,telephonic or other signals or messages, utilizable for receiving thesignals or messages from all directions, and more particularlyutilizable as a radio compass, direction finder, interference preventer,etc., in receiving signals or messages from a particular direction orstation to the exclusion or reduction of effects from other directionsor stations.

In accordance with my invention, the receiving apparatus, or a suitablepart thereof,

is shielded, as by enclosure within a chamber whose walls are ofconducting material, as sheet copper or other metal, or suitably finemesh metallic wire, or equivalent; and the shield is connected to thereceiving apparatus or suitable part thereof in such wise as to enhanceor increase the symmetry of the shield with respect to the receivingcircuits or apparatus.

My invention resides in apparatus of the character hereinafter describedand claimed.

For an illustration of some of the various forms my apparatus may take,reference is to be had to the accompanying drawings, in which:

Fig. 1 is a diagrammatic view of a receiving system provided with ashield in accordance with my invention.

Fig. 2 is a diagrammatic view of a modified arrangement.

Fig. 3 is a diagrammatic view of a radio compass, interferencepreventer, direction finder or other directional receiving apparatusprovided with a shield applied in accordance with my invention.

Fig. 4 is a diagrammatic view of a modification of apparatus ofthecharacter illustrated in Fig. 3.

Referring to Fig. 1, A is an antenna or any is the primary P of anoscillation transto the shield, as at a, the shield itself be-.

ing connected to earth or suitable counterpoise capacity E. The primaryP is, therefore, in efi'ect connected between the obsorption structure Aand earth or countercapacity E. Suitably related to the primary 1 is atuning condenser C. The condenser C is preferably in shunt to theprimary P for long waves and in series therewith for short waves. Thesecondary S of the oscilation transformer is shunted by the tuningcondenser C in parallel with which are connecked the serially relatedcondensers C and C from a point between which a connection is made byconductor 1) to the shield K and/or the earth or counter-capacity E. Thecondensers C and C may be adjusted or varied in opposite senses, orcomplementarily, to

such extent or in such wise that the shield K -inent or cathode f isconnected to the opposite terminals of the secondary S and condenser Cand to one terminal of the condenser G The filament f is supplied bycurrent from the battery I) delivering current through the adjustableresistance 1'. The battery D is preferably located within the shield Kand insulated from earth, or from the shield, or from both. In thecircuit of the anode p is the battery B and also a Winding T, which maybe that of a signal translating instrument, or of any suitable couplingfor controlling one or more subsequent stages of thermionic or otheramplifiers, rectifier-s or detectors.

In the arrangement above described, it will be noted that the shield Kis connected to an electrical mid-point of a receiving circuit, wherebythe shield not only prevents elec- -trical eii'ccts other than thoseabsorbed by K, as at a.

or electrical effects as may accumulate upon or affect the shield K fromaffecting the receiving circuit, since the latter is symmetrically or soconnected to the shield that its effect upon the receiving circuit issubstantially nil.

While difierent: connections a and-b are shown as made to the shield, itwill be understood that they may be one and the same connectiofi';

Or the connections a and b, or either of them, may be made to earth orcounter-capacity E without connection to the shield K.

In Fig. 2 is shown a generally similar arrangement to that shown in Fig.1, except, however, that the connection for veil'ecting symmetry of thereceiver circuit is made at the electricalmid-point of the secondary Sof the oscillation transformer, the condensers C and C of Fig. 1 in thisinstance being unnecessary.

Referring to Fig. 3, A is a coil, preferably rotatable, and preferablyhaving substantially no distributed inductance and substantial- 1y nodistributed capacity.

To a suitable pointin the coil A,as an electrical mid-point 0, may bemade a connection through switch 8 with an additional capacity area,antenna, or other absorption structure F.

The terminals of the coil A extend into the interior of the shield K,and are connected to the terminals of the tuning condenser .C? fortuning the closed circuit A, C" to the frequency of the received energy.Shunting the condenser C are the serially connected condensers C and Ceither one or both of which, as in Fig. 1, is variable, both beingpreferably complementarily variable for effecting symmetry of the closedcircuit A, C with respect to a point between the condensers C and C fromwhich is made a connection to the-shield From the point between thecondensers C and C there is a connection also to the earth orcounter-capacity E, independently of. contact or connection with theshield K, through the variable inductance, as a variometer L, which maybe short circuited upon closure of the switch d. V is a double audion(in lieu of which may be used two separate vacuum tubes or audions)whose grids g, g are connected to opposite terminals of the condenser Cand Whose filament or cathode structure f is connected to the shield Kand also to a point between the condensers C and C The battery D has itsone terminal connected to the shield K and to a point between thecondensers C and C and delivers current through the variable resistance1' to the filament f. The battery D may be employed either inside of theshield K or outside of it.

The circuits of the plates or anodes pinclude the transformer primariesP and P differentially inductively related to the secondaries S and Sconnected in parallel with each other and to the filament and grid of asecond stage amplifier or vacuum tube V in Whose platecircuit may beutilized a signalcember13,1922. A 1

The arrangement of closed circuit with the open or antenna path providesmeans for determiningsense of direction of a source of electro-radiantenergy, or when *the antenna circuit is not effective, as when theswitch dis closed or/and when theclosed circuit is symmetrical withrespect to the antenna path, the rotatable coil A aloneafi'ects thevacuum tube V for determining bearings with great nicety, preventinginterference, etc.

In Fig. 3 the shield K is not directly connected to the earth orcounter-poise capacity E, but is connected thereto indirectly throughthe variometer L when the switch d is open. However, when the switch atis closed, the shield K is connected directly to earth orcounter-capacity E, and so are the other portions of the apparatusconnected to a point between the condensers C and C.

In the arrangement of Fig. 4, the shield K is directly connected toearth or counter-capacity I) and through the variometer L to a pointbetween the balancing condensers C C Connected in series with thecondenser C across coil A is the primary P of an oscillation transformerwhose secondary is S these windings forming a variable coupling with theclosed circuit A, (1*. Shunting the secondary S is the tuning condenserC in shunt to which are connected the serially connected condensers Cand C Complementarily variable for balancing or eliecting symmetry ofthe secondary circuit with respect to the shield K, by connecting-theshield K-to a point between these condensers. The vacuum tube or doubleaudion V is related substantially as in Fig. 3, the filament battery Dand one terminal of thefilament fbeing also connected .to a pointbetween the condensers C, C and to the shield K by the connection I).

\Vhat I claini is:

1. Radio receiving apparatus comprising absorption structure, a receivercircuit associated therewith, a conducting shield enclosing saidcircuit, a connection from said shield to said circuit at a point ofsaid circuit rendering the same electrically symmetrical with respect tosaid shield, and a connection from said shield to earth orcounter-capacity.

2. Radio receiving apparatus comprising absorption structure, awave-responsive device operatively related to said BbSOIPtlOIlstructure, an enclosing shield, a connection from said shield to a-pointelectrically between the terminals of said wave-responsive device forprocuring electrical symmetry with respect to said shield, and aconnection 3. Radio receiving apparatus comprising absorption structure,a receiving circuit inductively related thereto, a conducting shieldenclosing said circuit, a connection from said .shield to said circuitat a point of said circuit rendering the same electrically symmetricalwith respect to said shield, and a connection 'from said shield to earthor counter-capacity.

4:. Receiving apparatus comprising absorption structure, a receivingcircuit associated therewith, a pair of reactances connected in seriesacross saidcircuit, at least one of said reactances being variable, aconducting shield enclosing said circuit, and a connection from apoiutbetween said reactances to said shield.

5. R adio receiving apparatus comprising;

thermionic means, an impedance connected between electrodes of saidthermionic means, a shield, and a connection from said shield to a pointintermediate, the terminals of said impedance for effecting electricalsymmetry with respect to said shield. 6. The combination with a coilabsorbing energy directly from the natural media, of a closed circuit ofwhich said coil is a part, a shield enclosing a part of said closedcircuit other than said coil, a circuit within said shield inductivelyrelated to said closed circuit, a connection from an electrical midpointof said second circuit to said shield, and a connection from said shieldto earth.

7. Receiving apparatus comprising absorption structure, a circuitassociated therewith, a shield enclosing said circuit, a plurality ofthermionic devices, a connection from an electrical mid-point of saidcircuit to the cathode structure of said thermionic devices, and aconnection from said mid-point to said shield.

8. Rcceiying apparatus comprising absorp tion structure, a circuitassociated therewith, a shield enclosing said circuit, a plurality ofthermionic devices. a connection from an electrical mid-point of saidcircuit to the cathode structure of said thermionic devices, aconnection from said mid-point to said shield, and a connection fromsaid shield to earth or countor-capacity.

9, The combination with a closed circuit comprising inductance andcapacity, of a shield enclosing said circuit, a pair of reactanfeswithin said shield connected across said circuit, and a connection froma point between said reactances to said shield.

10. The combination with means for absorbing energy directly from thenatural media. of a closed circuit coupled thereto, a shield enclosingsaid closed circuit, a current path connected across said closedcircuit, a connection to said shield from a point in said pathcorresponding with an electrical midpoint, and a connection from saidshield to earth or counter-capacity.

11. The combination with means for absorbing energy directly from thenatural media, of a'closed circuit coupled thereto, a shield enclosingsaid closed circuit, a current path connected across said closedcircuit, a connection to said shield from a point in said pathcorresponding with an electrical midpoint, a pair of thermionic deviceswithin said shield and comprising cathode structure, anodes and controlelectrodes, said control electrodes connected to different points insaid closed circuit, and a connection from said cathode structure tosaid mid-point.

12. The combination with an inductance absorbing energy directly fromthe natural media, of a capacity in circuit with said inductance, a pairof reactances in series with each other connected to opposite sides ofsaid capacity, a plurality of thermionic devices comprising cathodestructure, anodes and control electrodes, a connection from said cathodestructure to a point between said reactances, connections from saidcontrol electrodes to opposite sides of said capacity, a translatingdevice controlled by the anode circuits of said thermionic devices, ashield enclosing said capacity, reactances and thermionic devices, and aconnection from said shield to a point between said reactances.

The combination with an inductance absorbing energy directly from thenatural media, of a capacity in circuit with said inductance, a pair ofreactances in series with each other connected to opposite sides of saidcapacity, a plurality of thermionic devices comprising cathodestructure, anodes and control electrodes, a connection from said cathodestructure to a point between said reactances, connections from saidcontrol electrodes to opposite sides of said capacity, a translatingdevice controlled by the anode circuits of said thermionic devices, ashield enclosing said capacity, reactances and thermionic devices, aconnection from said shield to said cathode structure, a connection froma point between said reactances to earth or counter-capacity, and tuningmeans in said connection.

14. The combination with an inductance absorbing energy directly fromthe natural.

media, of a capacity in circuit with said inductance, a pair ofreactances in series with each other connected to opposite sides of saidcapacity, a plurality of thermionic devices comprising cathodestructure, anodes and control electrodes, a connection from said cathodestructure to a point between said reactances, connections from saidcontrol elec trodes to opposite sides of said capacity, a

translating device controlled by the anodev circuits of said thermionicdevices, a shield enclosing said capacity, reactances and thermionicdevices, a connection from said shield to said cathode structure, aconnection from a point between said reactan'ces to earth orcounter-capacity, tuning means in said conof reactanceswithin saidshield connected across said circuit, a pair of ithermionic deviceswithin said shield and comprising cathode structure, anodes and controlelectrodes,

a connection from said cathode structure to a point between thereactances of said second pan and to said shield, connect ons from saidcontrol electrodes to opposite sides of said reactances of said secondpair, a translating device controlled by the anode circuits of saidthermionic devices, and a connection from a point between the reactancesof said first pair to said shield.

16. The combination with an inductance absorbing energy directly fromthe natural media, of a pair of reactances in circuit with saidinductance, a shield enclosing said rcactances, a circuit in said shieldcoupled to the circuit of said inductance, a second pair of reactanceswithin said shield connected across said circuit, a pair of thermionicdevices within said shield and comprising cathode structure, anodes andcontrol electrodes, a connection from said cathode structure to a pointbetween the reactances of said second pair and to said shield,connections from said control electrodes to opposite sides of saidreactances of said second pair, a translating device controlled -by theanode circuits of said thermionic devices, a connection from a pointbetween the reactances of said first pair to said shield, and tuningmeans in said last named connection.

17. Directional. radio receiving apparatus comprising a shield, arotatable coil external to said shield and absorbing energy directlyfrom the natural media, a wave-responsive device within said shieldoperatively related to said coil, means determining an electrical midpoint between terminals of said Waveresponsive device, and a connectionfrom said mid point to said shield.

18. Directional radio receiving apparatus comprising a shield, arotatable coil external to said shield and absorbing energy directlyfrom the natural media, a wave-responsive device within said shieldoperatively related to said coil, means determining an electrical midpoint between terminals of said wave-responsive device. a connectionfrom said mid point to said shield, and'a connection fromsaid shield toearth or counter-capacity.

19. Directional radio receiving apparatus comprising a shield, arotatable coil external to said shield and absorbing energy directlyfrom the natural media, a plurality of thermionic devices within saidshield and comprising cathodestructure, anodes and coritrol electrodes,means for establishing said cathode structure at an electrical mid pointbetween said control electrodes, a connection fromlsaid cathode'structure to said shield, means including said rotatable coil in aclosed circuit, and an antenna path connected to an ellectfi'iical midpoint of said circuit and to said s ne 20. Directional radio receivingapparatus "comprising a shield, a rotatable coil external to said shieldand absorbing energy directly from the natural media, a plurality ofther- 'mionic devices within said shield and comprising cathodestructure, anodes and control electrodes, means for establishing saidcath ode structure at an electrical mid point be- FREDERICK A. KOLSTER.

